My long-term goal is to use chimpanzees as a model by which to explore how the mother-infant relationship influences offspring health and development in humans. The objective of this study is to identify key stressors for female chimpanzees, and to investigate the relationship between maternal stress, maternal behavior, and offspring development and health. I will pursue the following specific aims: 1) To determine the socio-ecological correlates of female stress as measured by cortisol levels, 2) To characterize maternal behavioral styles, and to investigate the relationship between style and maternal experience, maternal stress, and offspring sex, 3) To develop an offspring progress panel of social and physical milestones, and 4) To investigate how maternal behavior is associated with offspring stress, health, and development. I will conduct this research among the wild chimpanzees of Gombe National Park, Tanzania. This study will combine a rich and dense long-term dataset with new behavioral and hormonal data. Detailed mother-infant data have been collected since 1970, from which I will determine age and sex appropriate developmental milestones. Health data, including observational clinical sign and parasite assessments, have been collected since 2004, from which I will investigate the relationship between offspring stress and health. To complement existing data, I will use non-invasive sampling for hormone analysis via fecal hormone extraction and collect behavioral data on juveniles and adolescents. The study community currently contains 22 mother-offspring pairs, including 3 orphans;long-term data are available on 39 mothers and 91 different mother-offspring dyads. Given their genetic and behavioral similarities to humans, chimpanzees represent a particularly useful system in which to investigate the complex influences of social status, access to resources, and stress on mother-infant relationships and its subsequent effects on offspring development and health in humans. The results may also provide insight into why single parenting is a deficiency in humans by comparing a closely related species that has evolved towards single mothering (chimpanzees) with one where bi-parental care is the norm (humans). This research is therefore relevant to the missions of the National Institutes of Health, particularly the National Institute for Child Health and Development which supports research geared towards increasing our understanding of child, adult, family, and community health.